“Fox is confirming it was a hydrogen explosion in the outer containment building. Serious but not unexpected, and believe it or not the reactor remains under control.”
—Of interest:
“New explosion reported at nuclear plant”:
UPDATE: TOKYO — Japan’s chief cabinet secretary says a hydrogen explosion has occurred at Unit 3 of Japan’s stricken Fukushima Dai-ichi nuclear plant. The blast was similar to an earlier one at a different unit of the facility...
Edano says the reactor’s inner containment vessel holding nuclear rods is intact, allaying some fears of the risk to the environment and public.
The No. 3 Unit reactor had been under emergency watch for a possible explosion as pressure built up there following a hydrogen blast Saturday in the facility’s Unit 1...
“At the risk of raising further public concern, we cannot rule out the possibility of an explosion,” Edano said. “If there is an explosion, however, there would be no significant impact on human health.”
http://www.chron.com/disp/story.mpl/world/7470502.html
I’m not a nuclear scientist, and all I know is what I’ve been able to pick up over the last few days being as picky and discriminate as I can about whose opinions I choose to listen to.
As I understand it, during an extreme emergency like they are experiencing right now, one of the necessary methods used to cool down the reactor vessel is to vent steam into the reactor building itself. That gives the short-lived radionuclides in the steam a chance to decay and dissipate, as opposed to just discharging the live steam directly to the atmosphere. (I suspect that is an option if necessary, but they ain’t there yet...)
As I understand it, during an extreme cooling loss emergency like they are experiencing now, due to the elevated temperatures inside the reactor, water molecules begin do “disassociate” into gaseous hydrogen and oxygen. Some of it forms a bubble in the top of the system and it has to be removed quickly in order to prevent an explosion inside the vessel. It’s mixed in with the steam that they vent, and it does not take long to accumulate an explosive mixture inside the top of the weather housing, which is what that square building is.
If anyone needs a review of what happens when you mix pure hydrogen and oxygen, just review the main engine start sequence of your favorite space shuttle. The reaction is very vigorous, even in relatively dilute gaseous form, as opposed to the cryogenic liquids the shuttle burns.
These explosions of gas are serious, and they do release some radioactive products. Because there is some damage to the fuel rods, (no the uranium oxide fuel, at least not yet) there is radioactive cesium and iodine in the steam that is vented, and when the O2 and H let loose it all gets expelled into the atmosphere. Yes, it is a radioactive release, but the products are fairly short lived and in very small amounts.
As far as I can tell, the reactors all had control rods successfully inserted within seconds of the beginning of the quake. As time goes on the cooling resources improve as more emergency support arrives. Time is everyone’s friend right now, and a steady hand is what’s needed to bring these events to a conclusion.
And any discussion of core meltdowns is flat out irresponsible, nothing less than inflammatory, a bold faced lie in face of the ample credible evidence to the contrary, and deserves to be shouted down with as much scorn as can be mustered.
The level of hysteria being promoted in the American media is both shocking and near criminally irresponsible.